maarp

I've been lurking on these boards for awhile. I've been shopping around for a B5 A4 as a second car...it would be perfect for my son to learn on. Safe, a good size - you know what I mean.

Anyway, I found a 2000 1.8TQ with just nder 200K. Everything you can see is immaculate, however I took it to my mechanic just before I wrote the cheque, and I'm glad I did. He found:

1) One upper control arm worn (this I expected after looking around in here)
2) Seepage around the rear tranny seal to the drive shaft
3) Seepage around the left rear differential

Are these biggies? Should I run? Is this normal and cars will run forever like this? There is no dripping, just seepage.

I appreciate your input.

sonic

the control arm needs to be changed asap...the other 2 you would have to look into more to find the root cause. Seals are not difficult to change in the rear. Just make sure its not something worse. Other then that no need to run!

maarp

Yeah, the control arm needs to be done for the safety. But I'm not sure what you mean by "something worse".

sonic

well by something worse, i mean that they could of taken off the rear dif cover...seen that it all needs to be replaced and put it back on...with no new seal it will not seal properly...also if the fluid has been leaking b4, and the reason its not leaking right now is because there is no fluid left in there...then you have something worse.

maarp

It doesn't look like the plug on the diff has been opened in years - it's all corroded, so there is no way of checking the fluid. I almost take that as a good sign that it hasn't been taken apart and put back together. However, as to the amount of fluid left in there.....

None of the bits under the car look like they're swimming in oil. There's not enough seepage to drip. Starting to sound like coin flip. Maybe I can talk him down a couple of grand. Hmm....

K04-S4

A good mechanic can change the rear diff seals and center diff output prop shaft seal for a reasonable rate. These are common fixes at higher mileage. The rear diff has two plugs, a magnetic drain plug on the bottom and a fill plug on the side. Remove the fill plug to check the oil level and ideal level is flush with bottom of fill plug hole or at worst ~1" below bottom of fill hole.

maarp

There's the issue - that's the plug that is corroded. I'm afraid that forcing it will break something.

K04-S4

Plug is likely 17mm Allen. Clean any debris out of the plug allen hole so that the key will bottom out. Clean the visible exterior threads with a wire brush and apply a quality penetrating oil. The fill plug will come out.

If you don't pull the plug you will never know the fluid level

maarp

I mentioned the seals to the seller, here is his response.

"About the seals, they are sweaty and they have been like that for years, since I owned the car. Nothing actually leaks, there has never been a drop of fluid in the driveway from it. Seals do get old and start to sweat. My 2004 Audi has the same sweaty transmission seal. I wouldn't jump in and replace them, because as your mechanic said it can get expensive, especially the transmission one. (~$400). The rear differential fluid on these cars doesn't need to be changed out, and since it never leaked or caused any noise / problems, it has not been touched. The rear diff is a fully sealed unit."

You guys are the experts (that's one of the reasons I came here) - does this sound ligit to you? Sweaty seals? Again, thansk for your insight.

K04-S4

Most of what is stated makes sense but I disagree with the seals "seeping and never leaking for years" as they will start leaking sooner or later. Suggest replace seals when they actually start dripping fluid. Obviously this takes diligence as some people say seals are "just seeping for years" while gearbox has actually run out of fluid. Remove the fill plug and check the fluid level to be sure as an inexpensive verification vs replacing a failed gearbox later.

The rear differential is not a sealed unit (seperate drain and fill plugs) and fluid does need to be replaced. Remember "Audi Lifetime Fluid" means lifetime of the Audi Warranty and not the lifetime of the Vehicle. Recommend fluid replacement anywhere between 100K to 150K KMs. For example I do my own and recommend every 100K KMs to ensure the vehicles last for a very long time.